Experts evaluate earthquake potential off Washington coast

The Northwest's largest earthquake zone, just off the coast, which is called the Cascadia Subduction Zone (highlighted above) mirrors the area where the quake rocked Japan last March. (Image courtesy Pacific Northwest Seismic Network)

In the eleven months since the massive quake and tsunami hit Japan, the world’s leading earthquake scientists learned that a mega quake in the Northwest could be a lot worse than experts have predicted.

The Northwest’s largest earthquake zone, just off the coast, which is called the Cascadia Subduction Zone mirrors the area where the quake rocked Japan last March.

From the data recorded there, the Seattle Times reports that experts now believe a mega-quake in the Northwest could be more severe.

They are now working to create a new analysis of the hazards off the coasts of Washington, Oregon and British Columbia.

One new theory is that the topography of the sea floor is the key. Flat and featureless bottoms, like the bottom off Washington’s coast, seem to experience mega quakes more often.

Fortunately, last week, a large earthquake off the coast of Oregon didn’t have the devastating impact of a mega-quake concerning researchers.

The National Earthquake Information Center in Golden, Colo., says a magnitude 6.0 quake off the Oregon coast caused no reported damage and only a smattering of reports from people who felt it as a weak jolt.

The shallow quake recorded at 7:31 p.m. on Feb. 14 more than 150 miles west of southern Oregon did not generate a tsunami.

Within about an hour, the information center’s website recorded 39 reports of people who reported feeling the quake. Most were in northern California and southern Oregon and characterized it was “weak” or “barely felt.”

U.S. Geological Survey geophysicist Dale Grant said in a telephone interview the quake occurred in a seismically active area and called it “not uncommon at all.”

In his words, “These are the ones we like – nobody gets hurt and there’s no damage.”

According the Pacific Northwest Seismic Network, the last known great earthquake in the northwest was in January, 1700, just over 300 years ago.

The Associated Press and 97.3 KIRO FM’s Chris Sullivan contributed to this report.